When piston bearing engines seize due to failure in the drive line or other engine components, damage to the connecting rods is common. Rods may bend, twist, draw, or become elongated. Regardless, any damage to the connecting rods render an engine less efficient and in some cases inoperable. Therefore, mechanics need a precise means for determining whether distortion exist and if so to what extent before attempting to restore an engine to its original condition.
Various patents have been granted on devices which are designed to detect and measure defects in connecting rods. Representative of the prior art devices include the following.
U.S. Pat. No. 1,436,104 to Husak discloses an engine connection rod test gauge which relates to the fittings of crank connecting rods for automobile engines. This device tests the parallelism of the piston-pins with the crank bearings and any deviation from accuracy can be corrected.
U.S. Pat. No. 1,575,797 to Shaw discloses a lining jig intended for use in testing the condition of engine connecting rods and determining whether they are straight.
U.S. Pat. No. 2,025,008 to Arp discloses a connecting rod and piston testing and alignment device adapted for use to check the accuracy and parallelism of connecting rod bearings and their perpendicularly to pistons.
While these devices would appear to operate reasonably well and generally achieve their objectives under the limited range of operating conditions for which they were designed these devices embody one or more of the following drawbacks.
Neither prior art device allows the operator to measure an individual rod's standard length to the thousandths of an inch or metric length to the millimeter. Furthermore, the prior art fails to allow the operator to measure an individual rod's vertical clearance. Additionally, there remains a need for an improved device which allows the operator to obtain with precision length and vertical clearance of a series of engine connecting rods of a variety of sizes and from these critical readings detect any deviation from the manufacturers specification.